Rotary compressor



April 24. 1928.

A, W. WHITCOMB ROTARY COMPRESSOR 2 Sheets-Sheet 1 Filed Nov. 20. 1924 'ggl rmwz April 24.1928.

A. W. WHITCOMB ROTARY COMa RES SOR Filed Nov. 20. 1924 2 SheutuSheet 2 Patented Apr. 24, 1928.

UNITED STATES ALONZO W. WHITCOMB, OF WORCESTER, MASSACHUSETTS.

ROTARY COMPRESSOR.

Application filed November 20, 1924. Serial No. 751,137.

This invention relates to an air or, gas compressor in the form of a rotary gear pump.

The principal. objects of the invention are to provide an automatic rotary compressor of the type in which the compression is accomplished by means of elements, one rotating inside the other, and having intermeshing teeth and in which two sets of these rotary elements are combined to form a compound compressor or pump; to provide a construction of this kind in which a high degree of efficiency is secured and a minimum wear of the parts takes place; and which is noiseless, durable, and reliable; and to provide an adequate self-lubricating arrangement there for operated by the pressure of the air or gas and requiring practically no attention.

Other objects and advantages of the invention will appear hereinafter.

Reference is to be had to the accompanying drawings, in which Fig. 1 is a front view of an electric air compressor constructed in accordance with this invention and shown partly in central section;

Fig. 2 is a sectionalview on the line 2-2 of Fig. 1;

Fig. 3 is a bottom plan of the upper pump looking at it with the separating plate removed;

Fig. 4 is a similar top plan of the lower pump; and Fig. 5 is a plan of the separating plate.

In the drawings I have shown an electric motor constituting the power unit direct c annected by flexible connection 9 to. the shaft 11 of the pump or compressor which is located in a casing 12 below the motor. This pump casing is located on top of the air tank 13 and is adapted to deliverthe air through a pipe or tube 14 into it. The air tank 13 is provided with a pipe 15 which has a gauge 16 to show the pressure and is connected with a reliable automatic pressure switch 19 for controlling the motor to keep the tank pressure between 125 and 150 pounds 'for example. It starts the motor at the lower pressure to which it is set and stops at the higher. The compressed fluid is delivered through a connection 17 to a hose 18 for use in any desired way.

I have shown the pump itself as of a compound type and comprising two rotary members 20 and 21 of the same diameter fixed concentr cally on theshaft 11. These constitute internal rotary elements of the pump and they are provided with gear teeth as 1s well understood in this type ofpumps. They mosh internally with rings 22 and 23. These rings 22 and 23 constitute the outer members of. the two parts of the pump or compressor and I provide them with gear teeth meshing with and fitting the teeth of the internal elements. In each case there is a stationary crescent-shaped member 24 and 25 respectively. located between the teeth of the inner one fit against the concave surface at their outer ends and the teeth of the outer member fit against theconvex surface at their inner ends. The shaft 11 rotates the two gears 20 and 21 with it and they rotate the outer rings 22 and 23. In each case the air or gas is admitted at one side and carried along part the crescent-shaped member on both sides of it around to the other side where the teeth cominc. into mesh compress it and force it out under pressure. It willbe noticed that the two pumps just described are of different sizes. That is, the gears are of difi'erent thicknesses, as one of them compresses the air to an initial pressure and the other to a final pressure. Between the two is located a stationary plate 26 having certain passages, as will appear. The two crescent-shaped members are located differently in the two cases, I find it convenient, practical and efiicient to locate their centers in such position that the lines connecting their centers with the center of the shaft will make, an angle of approximately 90 to each other. although this angle may be varied according to the character of the fluid to be compressed and other conditions.

These rotary members are located in a pump element 27 depending from the cap 28 which constitutes the closure of the casing 12. This element. of course, has a passage for the pump shaft 11 centrally located and it also has a pipe or passage 29 for admitting the air fromthe outside. This passage has a check valve .30 resting on spaced points to allow the air to flow down freely. It practically checks the upward flow of the air and oil so that it will fiow up gently when the pump stops. The air passes into-the upper pump 2022 at the point 31. The air asses around on both sides of the crescent-s aped piece 24 and is delivered into a port 32 in the plate 26. This port constitutes'the exhaust for. the first pump and the intake for the second. The air thus compressed to what I call the initial pressure passes around in the second pump on both sides of the crescentshaped member 25 and downwardly through a port 33 under full compression. This is delivered outwardly and then upwardly through a port 38 in the plate 26 into a passage 34 and to a pipe 35 which extends upwardly in the casing 12 and has a slanting open upper end. A fine copper wire gauze 36 is fixed to the pump and surrounds the space into which the air discharges. The latter two features cooperate to disperse the air and prevent it from agitating the oil in the pump casing. The flexible connection 9 prevents the weight of the armature resting on the pump shaft.

It will be noted that the casing 12 is filled up to a. certain level with lubricating oil. I have shown an opening 37 for introducing it. This oil is filled in to a point below the top of the pipe 35 and as the air in the casing isalways under pressure the lubricant also is under pressure. Now I have provided a passage 39 in the bottom of the shaft 11 which extends in from the bottom of the shaft a certain distance and then passes out radially to the surface of the shaft. In this way oil is forced up to lubricate the parts. The air pressure is depended upon for acoomplishing this result and it forces the oil up and all around the various parts so as to keep them fully lubricated. The surplus lubricant is forced up the tube 29 into a? pocket 40 in the top of the pump element 27 or rather in the cover 28. The oil will accumulate here after the pump stops. When the pump is not running it will be drained back through the pump by gravity so that when idle the pump is supplied with a considerable amount of oil. This is an improvement on the usual construction in which machines are drained of oil at all times when idle.

By this construction I secure a self contained machine in which the motor, pump and tank constitute a single unit. Being self oiling as explained, even when long inactive it practically needs noattention except to put more oil in the tank occasionally. As that is so large considerable variation in level will be of no conse uence. The machine operates automatical y and practically noiselessly. It has no valves or other parts that develop noise or wear materially and cause inefliciency. It is more durable than a reciprocating pump would be and it has only one shaft to take care of.

Although I have illustrated and described only a single form of the invention I am aware of the fact that modifications of the invention can be made therein by any person skilled in the art without departing from the scope of the invention as expressed in the claims. Therefore, I do not Wish to be limited to all the details of construction herein shown and described, but what I do claim is 1. In a rotary compressor, the combination with a casing and a vertical central driving shaft, of a gear-shaped rotary member fixed thereto, a ring outside said rotarymember and having the same thickness and provided with teeth on the inner surface meshing with the teeth on the gear at one side, a crescent shaped member located in fixed position to fill the space between the two. toothed members, and means for discharging compressed air or gas from the pump into the casing, said casing being filled with lubricant up to a lower level and the shaft being provided with an exposed passage extending into it at the bottom and communicating with the exterior of the shaft to conduct lubricant up from the bottom under the pressure of the air or gas in the casing and distribute it around said gears.

2. In a compound rotary compressor or pump, the combination with an internal and an external gear meshing together and of the same thickness and having a crescentshaped stationary member between them to fill the space where they are spaced apart, a second pair of gears of the same nature and provided with a corresponding crescentshaped member, the inner gears of both sets being fixed on the same shaft about 90 degrees apart, and a stationary plate located between the two pairs of gears and extending throughout their areas, said plate having a port therethrough constituting an exhaust port for one pair of gears and at the same time an intake port for the other palr of gears.

In testimony whereof I have hereunto affixed my signature.

ALONZO W. WHITCOMB. 

